1. Field of the Invention
The present invention relates to a system or device for optically detecting an object and more particularly to a system or device for optically detecting an object, which system or device has a simple structure and which can be easily handled.
2. Description of the Related Art
Various structures are known as devices for detecting the existence of an object. For the purpose of detecting an object without affecting the object to be detected, a noncontact detector may be desirable.
A radiation transmitting photoelectric converter, such as a photo-coupler or photo-interrupter, having a radiation source section and a radiation detector section can be used for signal transmission or object detection system, for example. In such a photoelectric converter, the radiation source section and the radiation detector section co-operate to produce an electrical output through optical coupling. Basically the radiation source section includes a set of current supply leads and a radiation source element, whereas the radiation detector section includes a set of power supply leads, a radiation detector element, and an output signal lead connected to the coupling point between those elements. When the output signal is desired to have a higher transition signal level, an amplifier element is further incorporated. Assuming that the number of outgoing leads is five or more, for example, five or more coupling components and five or more coupling or assembling man-power steps are required.
For example, in an automatic machine for transporting or working an object or objects, a number of devices for optically detecting an object are used for operation control. When 100 optically object-detecting devices, each having five leads, are used, 500 leads are required, resulting in many connecting parts, much material, much man-power and space.
When it is determined whether an object is present or not, the signal is desired to be stable in each state and clearly change in transition in accordance with the presence or absence of an object. In the prior art, a stable and highly reliable signal was derived by amplifying the output of the photo-interrupter in a Schmitt trigger circuit.
As for the general knowledge of the prior art, reference may be made to circuit diagrams shown in data books or manuals of various manufactures such as "Photosemiconductor elements Data book" and "Semiconductor News No. 35" both published by Matsushita Electronics Corp.